Heyes.GetOpt.cs

using System;
using System.Collections;

namespace Heyes
{
	/// <summary>
	/// The GetOpt class allows you to easily define and handle
	/// command line options and arguments. Various styles of
	/// options are catered for each optionally having its own
	/// argument. For example: long options: (--foo), long options
	/// with arguments (--foo=bar), short options (-f, /f), short
	/// options with arguments (-f bar, -fbar) and consolidated
	/// short options (-fb).
	/// </summary>
	/// <example>
	/// This example defines 4 options (a, b, foo and bar). "foo"
	/// is required to be given with an argument (eg. --foo=xyz)
	/// and bar can be supplied with or without an argument.
	/// <code>
	/// try {
	///		GetOpt foo = new GetOpt(args);
	///		GetOpt.SetOpts(new string[] {"a", "b", "foo=", "bar=?"})
	///		GetOpt.Parse();
	///	} catch (ArgumentException e) {
	///		myProgram.PrintUsage();
	///	}
	/// </code>
	/// </example>
	public class GetOpt
	{
		#region Internal structure

		/// <summary>
		/// The CommandlineOption struct is used for representing
		/// a single option, with or without its argument.
		/// </summary>
		internal struct CommandlineOption
		{
			internal string option;
			internal string arg;
			internal bool argPresent;
			internal bool argRequired;
			internal bool argOptional;
		}

		#endregion

		#region Class fields

		private bool parsed;
		private string[] args;
		private ArrayList givenArgs;
		private Hashtable givenOpts;
		private Hashtable shortOpts;
		private Hashtable longOpts;

		#endregion

		#region Class properties

		/// <summary>
		/// Returns an ArrayList of supplied arguments (not options).
		/// If no arguments are supplied (ie none option args) then this
		/// will be empty.
		/// </summary>
		public ArrayList Args
		{
			get
			{
				return givenArgs;
			}
		}

		#endregion

		#region Class methods

		/// <summary>
		/// Constructor for the GetOpt class. Pass it the programs args
		/// list.
		/// </summary>
		/// <param name="args">The args as supplied to the Main() method.</param>
		public GetOpt(string[] args)
		{
			this.args = args;
			this.parsed = false;

			this.givenArgs = new ArrayList();
			this.givenOpts = new Hashtable();
			this.shortOpts = new Hashtable();
			this.longOpts = new Hashtable();
		}

		/// <summary>
		/// Defines the options you require for your program. You should
		/// pass if the options as a string array. There are two modifiers
		/// you can use to specify option arguments. Use "=" at the end of
		/// your option to specify that this option has to have an argument,
		/// and use =? at the end of your option to specify that an argument
		/// is optional.
		/// </summary>
		/// <example>
		/// <code>
		/// GetOpt.SetOpts(new string[] {"a", "b", "foo=", "bar=?"})
		/// </code>
		/// </example>
		/// <param name="options">
		/// A string  array of the options without the preceding
		/// "-", "--" or "/".
		/// </param>
		public void SetOpts(string[] options)
		{
			foreach (string option in options)
			{

				CommandlineOption optionStruct = new CommandlineOption();

				// Argument required
				if (option.EndsWith("="))
				{
					optionStruct.option = option.Substring(0, option.Length - 1);
					optionStruct.argRequired = true;

					// Argument optional
				}
				else if (option.EndsWith("=?"))
				{
					optionStruct.option = option.Substring(0, option.Length - 2);
					optionStruct.argOptional = true;

					// No argument
				}
				else
				{
					optionStruct.option = option;
				}

				if (optionStruct.option.Length == 1)
				{
					this.shortOpts.Add(optionStruct.option, optionStruct);
				}
				else
				{
					this.longOpts.Add(optionStruct.option, optionStruct);
				}
			}
		}

		/// <summary>
		/// Initiates the parsing of the options/arguments supplied
		/// to the program.
		/// </summary>
		/// <exception cref="System.ArgumentException">
		/// Thrown when: 1) an option is supplied with an argument and
		/// it shouldn't be, 2) an option is required to have an argument
		/// and it isn't supplied with one and 3) an option is supplied
		/// that has not been defined.
		/// </exception>
		public void Parse()
		{
			this.parsed = true;

			bool allowOptions = true;

			for (int i = 0; i < this.args.Length; ++i)
			{

				CommandlineOption optionStruct = new CommandlineOption();
				int idx;

				string arg = this.args[i];

				// no more options 
				if (arg == "--")
				{

					allowOptions = false;

					// Long option
				}
				else if (arg.StartsWith("--") && allowOptions)
				{

					// Option has an argument (eg --foo=bar)
					if ((idx = arg.IndexOf("=")) != -1)
					{
						optionStruct.option = arg.Substring(2, idx - 2);
						optionStruct.arg = arg.Substring(idx + 1);
						optionStruct.argPresent = true;

						// Option doesn't have an argument
					}
					else
					{
						optionStruct.option = arg.Substring(2);
					}

					// Checks
					if (!this.longOpts.ContainsKey(optionStruct.option))
					{
						throw new ArgumentException("Unknown option specified", optionStruct.option);

					}
					else if (((CommandlineOption)this.longOpts[optionStruct.option]).argRequired && optionStruct.argPresent == false)
					{
						throw new ArgumentException("Option requires an argument", optionStruct.option);

					}
					else if (((CommandlineOption)this.longOpts[optionStruct.option]).argOptional == false
							 && ((CommandlineOption)this.longOpts[optionStruct.option]).argRequired == false
							 && optionStruct.argPresent == true)
					{
						throw new ArgumentException("No argument permitted for this option", optionStruct.option);
					}

					// Add to defined options hashtable
					this.givenOpts.Add(optionStruct.option, optionStruct);

					// Short option(s)
				}
				else if ((arg.StartsWith("-") || arg.StartsWith("/")) && allowOptions)
				{

					optionStruct.option = arg.Substring(1, 1);

					// Is this option defined?
					if (this.shortOpts.ContainsKey(optionStruct.option))
					{

						CommandlineOption definedOption = (CommandlineOption)this.shortOpts[optionStruct.option];

						// Check for arguments to the option
						if (definedOption.argOptional || definedOption.argRequired)
						{
							if (arg.Length > 2)
							{
								optionStruct.argPresent = true;
								optionStruct.arg = arg.Substring(2);
							}
							else if ((i + 1) < args.Length)
							{
								optionStruct.argPresent = true;
								optionStruct.arg = this.args[++i];

								// No option, but one was required
							}
							else if (definedOption.argRequired)
							{
								throw new ArgumentException("Option requires an argument", optionStruct.option);
							}

							// No argument optional or required, so if arg is more
							// than just one letter, it could be multiple consolidated
							// options.
						}
						else if (arg.Length > 2)
						{
							this.args[i] = "-" + arg.Substring(2);
							--i;
						}

						// Add to defined options hashtable
						this.givenOpts.Add(optionStruct.option, optionStruct);

					}
					else
					{
						throw new ArgumentException("Unknown option specified", optionStruct.option);
					}


					// Not an option, an argument
				}
				else
				{
					this.givenArgs.Add(arg);
				}
			}
		}

		/// <summary>
		/// Returns true/false as to whether an option has been supplied.
		/// </summary>
		/// <param name="option">The option in question</param>
		/// <returns>Whether the option was given</returns>
		/// <exception cref="System.Exception">
		/// Thrown when the Parse() method has not been called.
		/// </exception>
		public bool IsDefined(string option)
		{
			if (this.parsed)
			{
				return this.givenOpts.ContainsKey(option);
			}
			else
			{
				throw new Exception("Call the Parse() method first");
			}
		}

		/// <summary>
		/// Returns true/false based on whether the given option has
		/// an argument or not.
		/// </summary>
		/// <param name="option">The option to check</param>
		/// <returns>Whether the option has an argument</returns>
		/// <example>
		/// <code>
		/// if (optionParser.IsDefined("bar") &amp;&amp; optionParser.HasArgument("bar")) {
		///		...
		/// }
		/// </code>
		/// </example>
		/// <exception cref="System.Exception">
		/// Thrown when the given option is not defined
		/// </exception>
		public bool HasArgument(string option)
		{
			if (this.IsDefined(option))
			{
				return ((CommandlineOption)this.givenOpts[option]).argPresent;
			}
			else
			{
				throw new ArgumentNullException("Option ({0}) is not defined");
			}
		}

		/// <summary>
		/// Returns the supplied options argument. Throws an exception
		/// if option does not have one.
		/// </summary>
		/// <param name="option">The option you want the argument for</param>
		/// <returns>The options argument</returns>
		/// <example>
		/// <code>
		/// if (optionParser.IsDefined("bar") &amp;&amp; optionParser.HasArgument("bar")) {
		///		string optionArg = optionParser.GetOptionArg("bar");
		/// }
		/// </code>
		/// </example>
		/// <exception cref="System.Exception">
		/// Thrown when the supplied option does not have an argument
		/// </exception>
		public string GetOptionArg(string option)
		{
			if (this.HasArgument(option))
			{
				return ((CommandlineOption)this.givenOpts[option]).arg;
			}
			else
			{
				throw new Exception("Option does not have an argument");
			}
		}

		#endregion
	}
}